Light Emitting Diode (LED) is widely used as a light source for advantages of low power dissipation and high light efficiency. A prior art LED power supply system adopts a single stage Power Factor Correction (PFC) voltage converter to drive LED. However, a single stage PFC voltage converter usually contains high output ripple. In order to decrease the ripple, a prior art solution adopts a large capacitor with high capacitance at the output of the voltage converter. However, this solution requires a large electrolyte capacitor which consumes large space and has short lifetime, and shortens the lifetime of the LED power supply system dramatically.
A prior art solution adopts small output capacitor with additional ripple suppression circuit for suppressing the output ripple. However, a traditional ripple suppression circuit is energy consuming and has low system efficiency.